1. Field of the Invention
The present invention relates to the field of integrated circuit manufacturing and more particularly to the formation of a strain enhanced mobility bulk nonplanar transistor and its method of fabrication.
2. Discussion of Related Art
Modern integrated circuits, such as microprocessors, are made up of literally hundreds of millions of transistors coupled together. In order to improve the performance and power of integrated circuits, new transistor structures have been proposed. A nonplanar transistor, such as a tri-gate transistor, has been proposed to improve device performance. A tri-gate transistor 100 is illustrated in FIGS. 1A and 1B. FIG. 1A is an illustration of a overhead/side view of a tri-gate transistor 100 and FIG. 1B is an illustration of a cross-sectional view taken through the gate electrode of a tri-gate transistor 100. Tri-gate transistor 100 includes a silicon body 102 having a pair of laterally opposite sidewalls 103 and a top surface 104. Silicon body 102 is formed on an insulating substrate including an oxide layer 106 which in turn is formed on a monocrystalline silicon substrate 108. A gate dielectric 110 is formed on the top surface 104 and on the sidewalls 103 of silicon body 102. A gate electrode 120 is formed on the gate dielectric layer 110 and surrounds the silicon body 102. A pair of source/drain regions 130 are formed in the silicon body 102 along laterally opposite sidewalls of gate electrode 120. Transistor 130 can be said to be a tri-gate transistor because it essentially has three gates (G1, G2, G3) which essentially form three transistors. Tri-gate transistor 100 has a first gate/transistor on one side 103 of silicon body 102, a second gate/transistor on a top surface 104 of silicon body 102 and a third gate/transistor on the second side 103 of silicon body 102. Each transistor provides current flow proportional to the sides of silicon body 102. The tri-gate transistor are attractive because they have large current per area which improves device performance.